text: 'use strict';
  
  var key = 'YOURAPIKEY'
    , SparkPost = require('sparkpost')
    , client = new SparkPost(key)
    , recipientList = {
      id: 'EXISTING_TEST_ID'
      , name: 'Test Recipient List'
      , recipients: [
        {
          address: {
            email: 'test1@test.com'
          }
        },
        {
          address: {
            email: 'test2@test.com'
          }
        },
        {
          address: {
            email: 'test3@test.com'
          }
        }
      ]
    };
  
  // Promise
  client.recipientLists.update(recipientList)
    .then(data => {
      console.log('Congrats you can use our client library!');
      console.log(data);
    })
    .catch(err => {
      console.log(err);
    });
  
  // Callback
  client.recipientLists.update(recipientList, function(err, data) {
    if (err) {
      console.log('Whoops! Something went wrong');
      console.log(err);
    } else {
      console.log('Congrats you can use our client library!');
      console.log(data);
    }
  });
  